Alternators Provide Steady Power for Floodlights
HAVING SUFFICIENT LIGHT inside a burning building is of great importance to the men who must put the fire out. And almost invariably, this light must come from a mobile power source to the affected building as soon as a fire is detected.
There are several ways to obtain power for this purpose, but in Omaha, the fire department gets it directly from the electric generating systems of its three hook and ladder trucks. Since 1957, we have used 1200-watt, 120-volt d.c. transformers connected to the output of the heavy-duty, 100-ampere, 12-volt alternators used to keep truck batteries charged.
The alternators supply sufficient amperage to overcome battery drain from a multiplicity of running and warning lights, sirens that need 125 amperes for building up to maximum pitch, and the operation of two-way radio while trucks are en route to fires.
Then, with truck engines running at idle speed, the alternators continue to produce up to 50 amperes of power to the batteries to compensate for the continued load of lights and radios, plus that required by the transformer to produce 1200 watts of d.c. current for the floods. By this means we have power for up to three 300-watt floodlights per ladder truck. These can be run into the building the moment a fire scene is reached. There is no waiting to fire up auxiliary equipment; light is available immediately.
Few if any restrictions are imposed by the electrical equipment. Power from the transformer (actually a compact mobile power supply) is supplied to the lights through 500-foot extension cords—long enough to meet all but the most extreme requirements. Voltage loss through the extension cords is negligible; we get virtually the full value of the lights’ 300-watt rating.
In cases where fires are especially difficult to extinguish, we frequently keep the lights burning for greatly extended periods. Doing so has led to no problems. As long as the ladder trucks’ engines are running, the lights operate without interruption. And never have we had a case of truck battery failure during an emergency.
The Omaha Fire Department’s rescue squad trucks are also equipped with heavy-duty alternators. Here their role is confined to the critical task of keeping batteries operable. No flood-lighting or other requirements for 120-volt power are involved. Hence, the rescue trucks are not equipped with transformers.
—Photos courtesy The Leece-Neville Co.
Batteries in these vehicles, however, are subjected to extremely heavy-duty service. For as in the case of ladder trucks, a large number of running and warning lights, two-way radios, sirens and other electrical gear requiring large amounts of 12-volt power are involved.
The need for absolute reliability again is unquestionable. More often than not, human lives depend on the ability of the trucks to get where they are needed, as quickly as possible. A battery failure anywhere along the line, literally, could be fatal. The alternators give us the best assurance against such an occurrence.